NEW DELHI: In a first, a genomic study of breakthrough infections In India at AIIMS, Delhi, during the peak of the second Covid wave, has confirmed that the disease in those vaccinated is a rarity. The study also shows that despite high viral dose and acute symptoms none of the vaccinated people succumbed to the infectious disease.
A total of 63 breakthrough infections -- mainly healthcare workers at the hospital itself -- had been seen at the tertiary care centre in April and May, which presented at the emergency indicating that they needed hospital care and were examined as part of the study carried by researcher at AIIMS and CSIR-Institute of Genomics and Integrative Biology.
The results have been published in the paper “Genomic analysis of symptomatic SARS-CoV-2 vaccine breakthrough infections from a tertiary care centre in India”.
Out of the 63 cases analysed, 36 patients had received two doses, while 27 had received one dose of vaccine. Also, while 10 patients had received Covishield, the rest had been administered with Covaxin.
“Our study has found that while breakthrough infections may be rare but are a reality mainly due to variants of concern and vaccines may be playing a significant role in reducing mortality,” said a scientist associated with the CSIR-Institute of Integrated Biology who is a co-author of the paper.
Viral load at the time of diagnosis was high in all the patients irrespective of vaccination status or type of vaccine received and the initial course of disease with high-grade non-remitting fever lasted for five to seven days in the vaccinated group, similar to the clinical presentation in unvaccinated patients, the paper said.
Of the 63 cases of vaccine breakthrough infections, including 36 who received full doses, there were no reports of mortality even though almost all cases presented with high-grade unremitting fever for 5-7 days, it added.
The examined cases in the scientific project closely overlapped and mirrored the Covid-19 cases in Delhi and the variants of concern B.1.617.2 and B.1.1.7 comprised the majority, but the proportions were not significantly different in comparison with the population prevalence of the variants during the period, according to the researchers.
While a number of vaccine breakthrough infections have been reported previously, it has been largely associated with non-severe symptoms.
The researchers also said that during the subsequent course of illness, neither disease worsening nor mortality was reported in the studied group, confirming the previous observations.
“While antibody levels for a subset of patients were available, they became infected nevertheless and presented to the emergency just like other patients, putting in doubt the protection offered and or clinical relevance of total IgG as a surrogate of Covid-19 immunity,” their paper said.
An observational study carried out at Indraprastha Apollo hospital in the capital last month had also shown that Covid19 vaccines are effective with vaccine breakthrough occurring only in a small percentage of vaccinated persons.
However, to understand the efficacy of the two vaccines being vastly used in India’s Covid vaccination programme, ICMR last week, as reported by this newspaper, has started examining their role in reducing hospitalisation and deaths in real world settings.